The exemplary embodiment relates to an apparatus and method for manipulations of graphic objects. It relates particularly to a tactile user interface which displays a virtual magnet that allows displayed graphic objects, such as text documents, to be manipulated as a function of attributes of underlying items that the objects represent, through finger or implement-guided movement of the magnet. Multi-touch interactive systems using specific user-interface designs and capabilities allow users to navigate easily through interactive content on multi-touch screens of interactive tables, interactive windows, multi-touch tablet computers, and multi-touch tablet PCs, all of which are referred to herein as tactile user interfaces (TUIs). TUIs incorporate a display device and touch-screen which detects user hand or implement movements. The detected movements are translated into commands to be performed, in a similar manner to conventional user interfaces which employ keyboards, cursor control devices, and the like.
However, translating the design of standard graphical user interfaces to multi-touch interactive devices is not always straightforward. This can lead to complex manipulations that the user may need to memorize in order to use the functionality provided by a touch-screen application. Additionally, hand movements often lack the precision which can be achieved with a keyboard and user fingers differ in size and shape, causing different touch signals to be sent from the touch-screen to the application.
For example, in the case of a large set of documents to be reviewed and classified, the repeated user actions of dragging each object, reviewing it, and then moving it to a selected file or other action may become wearing on the reviewer after an hour or two of such actions.
Another limitation of multi-touch interfaces is text-entry. Typing is often a requirement for entering data into a computer. However simply and accurately inputting text on tangible devices can be awkward for the user. While a physical keyboard could be plugged onto the multi touch-table, it may be confusing to the user to have to move repeatedly from screen interaction to keyboard interaction. Another option is to provide direct on-screen text-entry methods, such as soft keyboards, which are also known as virtual keyboards. A soft keyboard is an image of a keyboard on a touch screen. The user activates the keys by touch-tapping in a similar manner to touch-typing on a physical keyboard. In one such system, cameras may be positioned underneath the surface to capture an image of the user's hands and image recognition software employed to recognize the user's finger tips on the different virtual keys. This input is then processed by the computer and the result is displayed as text. In another system, an infra-red grid system is used. For example, a frame is permanently placed over an LCD screen with infra-red light senders and receivers placed on the frame edges. The soft keyboard can be rendered by displaying a keyboard image on the screen underneath the frame. The coordinates of the user's fingers intercepting the infrared beams by touching the key images are captured and transformed into text output.
In general, however, typing on soft keyboards is slower than on physical ones and tends to be less accurate. For the user, the tactile feel is also not the same as there is no force feed-back and if the user rests his fingers on or close to the key images, the device may register this as a key press. On projected systems, the shadows of the user's hands on the soft keyboard can sometimes blur the captured image of the selected keys and create inaccuracies. Another problem is that the keyboard display can obscure the other content of the display.